Process for forming adhesive-embedded fiber rods



L. S. MEYER Nov. 16, 1954 PROCESS FOR FORMING ADHESIVE-EMBEDDED FIBER RODS 4 Shee is-Sheet 1 Filed Feb. 12. 1952 INVENTOR. Leona/b 6. Meyer W. w 1

Nov. 16, 1954 s. MEYER 2,694,661

PROCESS FOR FORMING ADHESIVE-EMBEDDED FIBER RODS Filed Feb. 12. 1952 E 4 Sheets-Sheet 3 L. S. MEYER Nov. 16, 1954- PROCESS FOR FORMING ADl-lESIVE-EIBEDDED FIBER RODS Filed Feb. 12, 1952 4 Sheets-Shoo 4 mmvrm Leonam 8 Meyer BY United States Patent PROCESS FOR FORMING ADHESIVE-EMBEDDED FIBER RODS Lelofigl S.CMer, NewalllgJohlo, asslgnol' to Parallel cs 0 ewark, a-partnershlp consistin of Leonard's. Meyer and George A. Shin 8 Application February 12, 1952, Serial No. 271,184

18 Claims. (Cl."15491) My invention relates to a process for forming adhesrve-ernbedded fiber rods. It has to do, more particularly, with the forming ofsolid-or hollow rods or tubes, straight or tapered, which includes an outer skin or wall of glass fibers which :are embedded .in a. resin.

In .the patent issued to-Arthur M. Howaldand Leonard S. Meyer onOctober -16, 1951. No. 2,571,717, there is disclosed a continuous process for forming rods of adhesive-embedded fibers. The rods are made by .covering a core material with a .skin of longitudinally extending high tensile strength filaments or fibers embedded in a matrix of a hardy adhesive. According to such patent, the core material mayzbe of any light wood, hardened foamed resin, .or any. similar lightweight material which isstrong in compression. The fibers in the skin are preferably. high tensile strength glass fibers embedded n the hard adhesive, which bonds to the glass fiber material and to the core material. A polymerizable unsaturated polyester or a diallyl ester may be used as the hardenable adhesive. Resins of this type and which have been found satisfactory as binders-for glass fibers are disclosed in U. S. Patents Nos. .2,462,042 to Arthur M. Howald et a1; 2,255,313 to Ellis; and 2,388,319 to Fuller.

In manufacturing the rods according to such patent, the filaments or fibers are coated with the adhesive and are stretched longitudinally as they are placed in juxtaposed position and are held in a bundle surrounding the surface of the core material while the adhesive hardens. The adhesive-coated filaments are arranged in a uniform layer if the rod is to have uniform strength in all directions and are arranged non-uniformly if the rod is to have various strengths in difierent directions. Immediately after the bundling operation, a binding tape is helically wound onto the surface of the-skin enclosing the core material in order to hold the filaments and adhesive in place during the hardening or setting of the adhesive. This binding tape is usually of material which will not adhere to the resin andcan, therefore, be stripped therefrom or is of such a nature that it can remain permanently on the rod. When removedfrom the rod, the-tape leaves a helical ridge, where the resin seeps between the edges of the convolutions, or if the tape stays in place, the binding tape itself provides a rough surface. For some purposes the rough surface on the rod is not objectionable but for other purposes, for example, for use in making arrows to be shot from a how, the rough surface makes the rod useless for that purpose.

It is, therefore, the main object of this invention to provide a process for forming solid or hollow rods with an outer skin or wall of longitudinally extending high tensile strength fibers embedded in a matrix of hard adhesive and whereby the resulting rods have absolutely smooth surfaces which makes them suitable for many purposes for which the prior art rods of the same, general type were not suitable due to their rough surfaces.

In the accompanying drawings I have illustrated how my method can be performed. In these drawings:

Figure I is a diagrammatic view illustrating how a rod may be formed continuously, the smooth surface being produced on the rod by enclosing it before the adhesive is hardened in a molding or embracing tube, the material of which is removed after the adhesive is hardened.

Figure II is a transverse section taken on line I-I-II 2,694,661 Patented Nov. 16, 1954 of Figure I=showing the rod 'ustafter it .is enclosed within the molding or embrao ng tube.

Figure'III is a similar section-taken on the line III-III of-Figurehshowingthe tube after-the adhesive is hardened but before the molding or embracing tube material is removed.

Figure IV-is another similar section taken on line Iv -IV of -Fi e 1 showing the completed rod and after-the molding or embracing tube material has been removed.

Figure V is a perspective view of a short length of the.completed rod.

Figure VI is a longitudinal sectional view showing how-the core used in the method illustrated in Figure I can be tapered instead of straight.

Figure. VII is. a diagrammatic -view illustrating another way .of removing the material of the molding or embracing tube.

. Figure VIII- is a view similar to Figure I but illustratinga mandrel insteadof a core so-that a hollow rod or tube can beformedlnstead of asolid rod.

Figure [X is a transverse section taken .on line IX--IX of ,Figure. VIII v showing i the completed tube.

F X is alongitudinal sectional view showing how a tapered-mandrel can-.be used instead of the straight mandrel .of Figure'VIII.

Figure XI is a longitudinaisectional view illustrating how scouting may be appliedto. the rod before curing instead of the molding and embracing tube as in Figure I.

Figure vXII is a VIGW' mainly in longitudinal section illustrating a-mqdificationof the method for forming the smooth surface on the rod, the molding or embracing being a permanent mold with a means. in thismstance flexible tubular mold cavity.

Figure XIII is atranaverse sectionjaken on line XIII- Iof lllll'b .(II showing the rod in the mold.

Figure V is a transverse section taken on line XIV XIV .of Fi re XII showing the completed rod.

Figure is a View similar to Figure XII but showing an l:ldhesive bath through which the fibers pass before mo mg.

Figure XVI is a viewrliite. Figure XV but showing the apgyratus vertical instead of horizontal.

, tgure XVII-is a longitudinal sectional view illustrating a different type of mold with a flexible tube cavity for producin the smooth surface .on the rod.

Fl e XV III is a transverse sectional view taken on line inn .xv1n of Figure showin therod in the mold cavity before the. avail thereof em races it.

Figure is. a v ew similar to Figure XVIII but showing the mold .caVltyembracmg the rod.

e'XX is a transverse section taken on line XX- XX of Figure XIX showing the completedrod.

.In. the following desc tion I shall referto the, fibers as being, 2188s fibers the adhesive as being aresin but, as previously ind ated other materials may be used.

.With reference to the drawings, in Ft e vI, .I have illnsttated one methodotmakmg .a re according to my invention. Bythis methodlong rodspan be formed in a substantially continuous process. is method involves bundling a Plural: of bla -ten e strength glass fibers on a core o ,suitab e compressive streng As shown, .aplurality of the glass fibers 30 are continuously drawn from the pbbinslil which are carried on the bobbin plate 32. At the same time the core 33 is fed continuoudy over a suitable support 34. The glass fibers are drawn under tension through .circular combs 35, at the center of the bobbin plate 32, and the .core 33 is also drawn throus the center ofthese' combs. The glass. fiber may have been mpregn ted with or coated with uncured resinpreviously or the fibers may bepassed tbrougha bathv of uncured res n illustrated at 36. The glass fibers -30 and the. associatedcore 33 are drawn into the bundling ring .37 where .the fibers are guided into close contact with and around .the core 33 covering it witha layer of the uncured resin and glass fibers. Thislayer mayhave thettibers uniformly arranged around it, resulting from the uniform guiding arrangement provided by combs 35, or the fibers may bo arrangcd nonuniformly around the layer if it is desired .to have more tensional strength on one side or the other of the rod.

After leaving the bundling ring 37 and before the resin is cured, the core 33 with the layer of resin and fibers thereon is then drawn into a ring unit 38 which will apply a molding or embracing film tube 39. The film tube 39 is preferably in the form of an annular roll 40 which unwmds at its center and through which the core 33 and surrounding layer are drawn. This roll 40 of material bears against a cradle formed in the rear side of a fiange 41 which is part of the unit 38. The ring unit 38 includes the funnel-shape part which is directed forwardly and which serves to guide the fiber around the resin-fiber layer on the core 33. The film tube 39 is formed of resilientmaterial and will be stretched, when pulled along by the core and surrounding resin-fiber layer, as it is unwound from the roll 40. In stretching, it is reduced in diameter and will tightly embrace the resin-fiber layer forming a smooth surface thereon. In starting the operation the forward or leading edge of the film tube may be suitably clamped or cemented to the resin fiber layer so that it will be pulled along by forward movement of the core 33 which is surrounded by the resin layer.

The film tube 39 is of special resilient material which will shrink and more tightliyl!a gri the resin-fiber layer when heated during the res cung o ration, for exam le, at a temperature of between 1 and 200 F. an which can be disintegrated b further heat, for example, at about 375' F. I have ound that a vinylidene chloride plasticized material is suitable for this Such a material is sold by the Dow Chemical mpany under the trade-name Saran.

When the enclosed core leaves the unit 38 it will a& pear in cross-section as in Figure H. The core 33 will surrounded by the layer 42 of uncured resin and fibers and this layer will be surrounded by and tightly gripped by the film tube 39. The enclosed core is continuously and progressively drawn throu the heating and curing unit 43 where the temperature is raised sumciently, about 200 F., to cure the resin. As the resin is heated for curing, the film 39 is heated which, as indicated above, causes it to shrink and more tightly embrace the resinfiber layer 42. Consequently, by the time the resin is cured the layer 42 is so tightly gripped that the cured layer 42a (Figure IH) will have a smooth outer surface.

The formed rod, enclosed by film 39, is continuously and progressively drawn through the film-disintegrating unit 44. In this unit, the rod is heated to a temperature of about 375 F. The resin used in layer 42a is preferably a thermosetting resin so that this heat will not harm the layer but it will be sufficient to cause disintegration of film 39. This film material will melt and form globules which will drop off the rod onto the bottom of unit 44 and can be removed therefrom in any suitable manner.

The finished rod thus formed is shown in Figures IV and V and consists of the core 33 surrounded by the cured resin-fiber layer 42a which will have a smooth outer surface.

Beyond the unit 44, the gripping channel rollers 45 are provided which serve to pull the enclosed core progressively and continuously through all the var ous units. It is understood that these rollers will be driven positively by some suitable means. Beyond the rollers 45, a suitable severing unit may be provided for dividing the rod into suitable lengths, for example, shears 46 may be provided for acting on the rod while it is moving.

The core 33 is illustrated as circular in cross-section in Figure I but it is to be understood that it could be of any desired cross-sectional shape. The film tube 39 will tightly embrace it regardless of its cross-sectional shape. The pull-through rollers 45 will have channels of complemental shape.

For some uses it is desirable to have the rods taper. If so. the core 33 will have the desired taper. Instead of a straight core as in Figure I, the core may be made up of several succeeding tapered sections. As shown Figure VI, the tapered core 33a will be fed with its small end leading. The tapered rod may be pulled by means of the gripping rollers 45a which are urged towards each other by springs 47 so as to compensate for the gradual increase in diameter of the rod. It will be understood that the channels in the rollers 45a will be of sufiicient cross-sectional area to compensate also for the increase in diameter of the rod.

Instead of using the heating unit 44 of Figure I to disintegrate the film 39 it may be disintegrated by subjectlng it instantaneously to a flame. This is illustrated diagrammatically in Figure VII where the jets 44a are provided for projecting ames on the film 39. If desired, the jets may be arranged in a circular burner through which the rod will pass.

the arrangement shown in Figure I, the core 33 remains in the rod, forming a solid structure. However, my invention is also applicable to the forming of a hollow rod or tube as shown in Figures VIII and X.

In this form of my invention instead of providing the progressively fed core 33, which becomes a part of the rod, I provide the stationary mandrel 33b. The mandrel 33b is shown as a straight mandrel and is clamped in fixed position by a supporting clamp 34a at its rear end. The tube 42b is forced off the mandrel by means of the gripping rollers like the rollers of Figure I which serve to support the forward end of the mandrel as well as to pull e resin-fiber layer or tube through the various units. Instead of forming the tube 42b, a hollow rod of any other desired cross-sectional shape may be formed, the pull-through rollers being changed to have channels of pro r cross-section for receiving and gripping the parti ar shape. Application of the film 39 will be the same as in Figure I and it will be understood that it will stretch sumciently as the tube 42b feeds progressively to compensate for the increase in diameter of the tube.

As shown in Figure X, instead of the mandrel being straight as in Figure VIII it may be tagered. The tapered mandrel 33c will have its small en forwardmost and the mandrel will be supported as in Figure VIII. However, the pull-through rollers will, in this instance, be yieldingly urged towards each other as in Figure VI so that they will spread apart as the, tapering tube 42c is pulled off the mandrel and its diameter increases.

Instead of applying a film tube 39 to the rod, as in Figure I, the rod may be actually coated with a suitable substance which will serve to impart a smooth surface thereto during curing and will later be removed. Thus, as shown in Figure XI, instead of the unit 38, a liquid bath 38a is provided so that the resin-fiber layer will pass therethrough before the curing operation.

The liquid in the bath 38a will be a film-forming liquid which is immiscible with the particular resin being a used and which will shrink when it dries. To dry it immediately after application and before the curing operation, I will provide a drying unit 38b for heating it to about 150 F., so that a dry film 39b will be formed thereon. Therefore, when the film 39b dries it will shrink and before the coated resin-fiber layer is cured, it will be tightly embraced thereby. The resin-fiber layer will be applied to a core 33d or to a permanent mandrel. Later the film 39b may be disintegrated by heating to a high temperature, for example, 375 F. or

itzgiay be stripped from the rod leaving the finished rod Two solutions which are suitable for this film-forming purpose are solutions of methyl cellulose or polyvinyl alcohol for use with resins such as polyester orv I epoxy. Other solutions such as ethyl cellulose, nitro cellulose, celiulose acetate and vinylidene chloride may be used with resins such as urea formaldehyde and resorcinol formaldehyde.

The liquid in the bath 38a, moreover, could be a hot film-forming melt which would be immiscible with the resin being used in forming the rod. This melt would cool quickly immediately after it left the bath or could be cooled by a suitable cooling unit used in place of unit 38b. For example, various melts such as waxes, liquid thermoplastics, and vinyl plastisols could be used with various resins, such as polyester or urea formaldehyde. Films formed from these hot melts could also be removed after the curing operation either by heating to a temperature substantially exceeding the curing temperature of the resin, for example, about 375 F. or by stripping.

In Figure XII, I have illustrated a different way of forming a smooth surface on the resin-fiber layer of the rod. In this case the resin-fiber layer, formed from previously impregnated or coated fibers, on a core or a permanent mandrel is passed through a mold having a moldcavity formed of a flexible wall which will be caused to tightly embrace the resin-fiber layer to form the smooth outer surface thereon.

51 having a mold cavity formed therein by means of a ZOQQGBH B flexible sleeve disposed! thereonrwith. its? endssuitalflyca ahltnof being-fdisintegrated-byrheatsm that whom the clampadtto: the ondsroi'. casingrfiii. The sloeverflcm OSiVOldOQQ' hardem thererwilli be-alsmooth'v continuous:

be: OfL rubben or." othen floxihle:matet:ialrandi is: of: 1 surface free ofiridges; treating therod lihezmass to harden size that there is a fluid chsmberrflrsun-uundingdt: im the adhesive, .and' hoating!the:encloscd:rod-likc:masstto the casingz5lt- Aisuitabletinleti 54 and.outletr-55-are.prodisintegrateathe moldingunaterial. videdtfon this=chamber:53.. 2. The method of claim 1 wherein'thealongitudinally' ln Figura- Xlli. l: have shown-the: resin fiber layen apsextendingi fihersr arerglassl fibers:- which. are: maintained plied to a core 33: but it is to be understood thae'thisa under'tensionranduthe; adhesiverisr an=uncnred;resin-,.andi could: be a mandrel: lnrinitiallyrstarthigttlite roditliro wherein: said: is 'heatedo tat cure: it; afterr the: molds this mold 50, the cavity thereof may be enlarged: y' ingnmatertal is applied thereto but before the material. vacuumizing chamber 53, thus permitting the rod to enter is atedlfonrdisintegration. thereintq freely. Then pressure, for-example, steam, can 3. Thermethodmficlaim twhereimthe saidzfibers and: be appliedirr chamber" 53 and cause the tube 52 to resin are-combinedeon a longitudinallyrextendihg suptrghtly embrace itlteirodtFigtueJflllilto fbnn the smooth rt. outer surface on the resin-fiber layer. as the surrounded- 1s- 4 Themethodiofinclaimr 3; wherein:the.-molding: met-- core. is'forced therethrough. If steamisused in.chamber terial is a longitudinally extending hollow member formed:

ofrvinylidene-plasticizedzmateri 3 thus formed, will appear in cross-section as iii-Figure St-"Ihemethod oftformingiavrod-whichrcomprises com- XW and will include com 332' and. the curedresinbining; a; lurality. ofa lhngitudinally; extending fibers fiber-layer'42e. 'and am esive: materialtcapablewf being: hardened In Figure XV,.I-illustrato the-use of the same mold 50 intoran' elongated mddikm massgflpassingr the rod-likebut the glass fibers are combined'in a bath 38b of resin mass: into: am elongated: mold. havingq-a; flexiblewall insteadfofi being: previmnlyvimpregnatedioncoated'with cavity havitigi a smooth continuous: molding wall: sunresin as in Figure XIIJ. face which isrexpandedintot embracing relationship with In Figure VI. h m rr ngemen of mold 50a is the rod-like mass before the adhesive hardens so that provided except that it is vertical. Also, the resin bath when it does harden there will be a smooth continuous 38c is vertical. surface free of ridges produced on the resulting rod, It will be apparent that when the process is carried treating the rod-like mass to harden the adhesive while out as in Figures XII to XVI it can be continuous if the embraced in the mold, and removing the resulting rod resin-fiber enclosed core or mandrel is passed through from the mold. the mold 50 continuously after it is once started. It 6. The method of claim 5 wherein the rod-like mass the other hand, the process could be intermittent, formis fed continuously through the mold. ing a length of the rod in mold 50 and then relieving the 7. The method of claim 5 wherein the adhesive is in pressure to permit the mold cavity to enlarge so that the the form of a resin which is applied to the fibers that are formed rod section can be received and a new section be glass by passing the fibers downwardly through a bath of placed in the mold 50. the resin before the mass enters into the mold, the wall In this form of my process also the rods formed can of the mold being heated to cure the resin while the rodbe of any cross-sectional shape depending on the shape like mass is therein. of the mold cavity. 8. The method of claim 7 wherein a support in the In Figure XVII, I have illustrated another type of mold form of a rod is also passed continuously downwardly 60 which may be used in carrying out my process conthrough the bath of resin and then into the mold. tinuously 0r intmnifiently- 9. The method of forming a rod which comprises com- The casing of this mold is formed by the telescoping bining a plurality of longitudinally extending fibers and sections 61 and 62 and provides an interior fluid chamber an adhesive capable of being hardened into an elongated 63 that is Provided with an and an Outlet 65 10 P rod-like mass, passing the rod-like mass into an elongated mit Steam or other suitable fluid to pass through chammold having a flexible wall cavity having a smooth conber 63. Centrally within chamber 63 a tube 66 of flexible tinuous molding wall surface, causing the wall surface to material, such as rubber, is provided and one end is embrace the rod-like mass before the adhesive hardens clamped to section 61 while the other end is clamped to so that when it does harden there will be a smooth consection 62. A suitable unit 67 is provided for expandtinuous surface free of ridges produced on the resulting ing and contracting the telescoping sections 61 and 62, rod, treating the rod-like mass to harden the adhesive the unit shown being mechanical. When the sections 61 while embraced in the mold and removing the resulting and 62 are expanded the material of tube 66 is stretched rod from the mold. and, therefore, it will become smaller in diameter and 10. The method of forming a rod which comprises when the sections are again telescoped, the tube will becontinuously and progressively combining a plurality of come larger again in diameter. longitudinally extending glass fibers which are main- The tube 66 will be in the enlarged state (Figure XVIII) tained under tension and an adhesive uncured resin when the core or mandrel 33f, with the resin-fiber layer capable of being hardened into an elongated rod-like thereon, is initially fed into mold 50 and then is conmass on a longitudinally extending support and enclosing tracted, with the surrounded core being subsequently fed 0 the rod-like mass within an elongated embracing molding therethrough continuously. The resin-fiber layer will at material having a smooth continuous molding surface this time (Figure XIX) be tightly embraced by the tube contacting the rod-like mass and being in the form of a 66. This will produce a rod 42 which (Figure XX) longitudinally extending hollow member of vinylidene will have a resin-fiber layer with a smooth outer surface, plasticized material capable of being disintegrated by heat the layer surrounding a core 33f. so that when the adhesive does harden there will be a The process can be intermittent also, the mold 60 actsmooth continuous surface on the rod-like mass, heating ing successively on sections of the resin-fiber enclosed the rod-like mass to cure the resin after the molding macorc. terial is applied thereto but before such material is It will be apparent from the above that I have proheated for disintegration, and heating the enclosed rodvided a process of forming hollow or solid rods with an 7 like mass to disintegrate the molding mater al by subouter skin or wall of longitudinally extending high tenjecting said hollow member to a flame instantaneously. sile strength fibers embedded in a matrix of hard adhesive, 11. The method of forming a rod which comprises h process being such that the outer surfaces pf h combining a plurality of longitudinally extending fibers rods produced will have a very smooth surface wi h he and an adhesive material capable of being hardened into result that the rods will be suitable for various purposes an l t d dJik mass, passing th d-1ik mass which Prlor rods Could 1101 be uscd because of into an elongated mold having a flexible wall cavity with then ffmgh Surfaces; a smooth continuous molding wall surface, enlarging the Hal/111g thus dcscrlbcd mvemlon; Whai I E 15: mold cavity to permit entrance of the rod-like mass in Th method of q s a q y comlfflses the initial movement of the mass thereinto and subsetinu usly and PIOETCSSIVCIY comblnlng a p j y 0f quently decreasing the mold cavity in size by expanding gitudinally extending fibers and an adhesive material it i to e bra ing el tion hi ith th dqik mass Capable of being hardtmed into an clongated rod-[Ike before the adhesive hardens to tightly grip the mass after mass and enclosing the rod-like mass within an elonthe feed thereof into the mold has begun so that when gated embracing molding material having a smooth conthe adhesive does harden there will be a smooth continutinuous molding surface contacting the rod-like mass ous surface produced on the resulting rod, heating the 53; this will: also serve" to" cure th'e'resin. The rod,

7 rod-like mass to harden the adhesive while embraced in the mold, and removing the resulting rod from the mold.

12. The method of claim 11 wherein the fibers are of glass and the adhesive is an uncured resin, the wall of the mold being heated to cure the resin while the rod like mass is therein.

13. The method of claim 12 wherein the fibers are impregnated with the resin before combining by passing ghegi through a resin bathcontinuously as they are com- 14. The method of claim- 13 wherein the fibers are combined upon a longitudinal! extending support.

15. The method 0 claim 4 wherein the core material and fibers are gassed downwardlci through a bath of the resin and then to the mold whi is vertically disposed.

16. The method of formin a rod which comprises combining a plurality of lo tudinally extending fibers and an adhesive material capable of being hardened into an elongated rod-likemass, enclosing the rod-like mass within an embracing material having a smooth continuous surface oentactin the rod-like mass by ap lying, before the adhesive h ens, an actual coating w ch does not combine with the adhesive 0! the rod so that when the adhesive does harden, there will be a smooth continuous surface produced on the resulting rod, treating the rodlike mass to harden the adhesive and removing the embracin material coating 17. e method a plied b passing hesive.

18. The method of elt.

of claim 16 wherein the coating is the rod-like mass through a liquid of g substance which is immiscible with the adclaim 17 wherein the liquid is a hot References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,407,549 ck Sept. 10, 1946 2,485,967 Harding Oct. 25, 1949 2,511,421 Werner June 13, 1950 2,571,717 Howald et a1 Oct. 16, 1951 OTHER REFERENCES Modern Plastics, Resin bonded glass fiber fiy-rod,

February 1946, pages 124 and 125. 

1. THE METHOD OF FORMING A ROD WHICH COMPRISES CONTINUOUSLY AND PROGRESSIVELY COMBINING A PLURALITY OF LONGITUDINALLY EXTENDING FIBERS AND AN ADHESIVE MATERIAL CAPABLE OF BEING HARDENED INTO AN ELONGATED ROD-LIKE MASS AND ENCLOSING THE ROD-LIKE MASS WITHIN AN ELONGATED EMBRACING MOLDING MATERIAL HAVING A SMOOTH CONTINUOUS MOLDING SURFACE CONTACTING THE ROD-LIKE MASS CAPABLE OF BEING DISINTEGRATED BY HEAT SO THAT WHEN THE ADHESIVE DOES HARDEN THERE WILL BE A SMOOTH CONTINUOUS SURFACE FREE OF RIDGES, TREATING THE ROD-LIKE MASS TO HARDEN THE ADHESIVE, AND HEATING THE ENCLOSED ROD-LIKE MASS TO DISINTEGRATE THE MOLDING MATERIAL. 